DLG2 intragenic exonic deletions reinforce the link to neurodevelopmental disorders and suggest a potential association with congenital anomalies and dysmorphism.

PURPOSE: Multiple studies suggest an association between DLG2 and neurodevelopmental disorders and indicate the haploinsufficiency of this gene; however, few cases have been thoroughly described. We performed additional studies to confirm this clinical association and DLG2 haploinsufficiency. METHODS: Chromosomal microarray analysis was performed on 11,107 patients at the Cytogenetics Laboratory at the University of Alabama at Birmingham. The Database of Genomic Variants-Gold Standard Variants and the Genome Aggregation Database were selected for the association analysis. Fifty-nine patients from the literature and DECIPHER, all having DLG2 intragenic deletions, were included for comprehensive analysis of the distribution of these deletions. RESULTS: A total of 13 patients with DLG2 intragenic deletions, from 10 families in our cohort, were identified. Nine of 10 probands presented with clinical features of neurodevelopmental disorders. Congenital anomalies and dysmorphism were common in our cohort of patients. Association analysis showed that the frequency of DLG2 deletions in our cohort is significantly higher than those in the Database of Genomic Variants-Gold Standard Variants and the Genome Aggregation Database. Most of DLG2 intragenic deletions identified in 69 unrelated patients from our cohort, the literature, and DECIPHER map to the 5' region of the gene, with a hotspot centered around HPin7, exon 8, and HPin8. CONCLUSION: Our findings reinforce the link between DLG2 intragenic deletions and neurodevelopmental disorders, strongly support the haploinsufficiency of this gene, and indicate that these deletions might also have an association with congenital anomalies and dysmorphism.

An Early Case of Complete Androgen Insensitivity Syndrome.

Inguinal hernias are rare in female infants, and when present, there is an increased incidence of androgen insensitivity in these infants. We present a case of bilateral inguinal hernias in a 26-day-old full-term phenotypic female. On physical exam, the patient was found to have bilateral palpable inguinal masses which were suspected to be testicular tissue on ultrasound. Patient also had bilateral inguinal hernias, but otherwise there were no other concerning symptoms, and the remaining physical examination was overall unremarkable. Initial workup included a pelvic ultrasound that did not visualize a uterus or ovaries. In addition, genetic testing confirmed normal male genotype with 100% 46, on fluorescence in situ hybridization (FISH) and array comparative genomic hybridization (CGH) was negative and did not reveal any copy number changes. Molecular testing was consistent with a diagnosis of androgen insensitivity syndrome with hemizygous pathogenic variant in the androgen receptor (AR) gene (deletion of Exon 2 of AR gene Xq12). This case highlights the importance of a high clinical suspicion of complete androgen insensitivity syndrome (CAIS) in a phenotypic female infant with inguinal hernias. To our knowledge, this is one of the earliest diagnoses of CAIS in a phenotypically female infant.

Novel variants in KAT6B spectrum of disorders expand our knowledge of clinical manifestations and molecular mechanisms.

The phenotypic variability associated with pathogenic variants in Lysine Acetyltransferase 6B (KAT6B, a.k.a. MORF, MYST4) results in several interrelated syndromes including Say-Barber-Biesecker-Young-Simpson Syndrome and Genitopatellar Syndrome. Here we present 20 new cases representing 10 novel KAT6B variants. These patients exhibit a range of clinical phenotypes including intellectual disability, mobility and language difficulties, craniofacial dysmorphology, and skeletal anomalies. Given the range of features previously described for KAT6B-related syndromes, we have identified additional phenotypes including concern for keratoconus, sensitivity to light or noise, recurring infections, and fractures in greater numbers than previously reported. We surveyed clinicians to qualitatively assess the ways families engage with genetic counselors upon diagnosis. We found that 56% (10/18) of individuals receive diagnoses before the age of 2 years (median age = 1.96 years), making it challenging to address future complications with limited accessible information and vast phenotypic severity. We used CRISPR to introduce truncating variants into the KAT6B gene in model cell lines and performed chromatin accessibility and transcriptome sequencing to identify key dysregulated pathways. This study expands the clinical spectrum and addresses the challenges to management and genetic counseling for patients with KAT6B-related disorders.